1. Field of the Invention
The present invention relates to a novel organic luminescent device.
2. Description of the Related Art
An organic electroluminescent device includes a thin film containing a fluorescent organic compound or a phosphorescent organic compound interposed between an anode and a cathode. Electrons and holes (positive holes) are injected from the electrodes into the thin film to form excitons of the fluorescent compound or the phosphorescent compound. The organic electroluminescent device utilizes the light emitted when the excitons return to the ground state.
Such organic electroluminescent devices have been studied actively.
Organic electroluminescent devices need an optical output of higher brightness or higher conversion efficiency, and these subjects are intensively studied. However, further improvement of organic electroluminescent devices is desirable in terms of durability such as change with time due to prolonged use and deterioration due to an atmospheric gas containing oxygen, moisture or the like.
It is believed that, even when a uniform amorphous film is formed at first, intermolecular interaction gradually causes crystallization or aggregation therein, leading to a change with time. Japanese Patent Application Laid-Open No. 2004-155711 discloses a technique to reduce the intermolecular interaction by coupling organic molecules at the respective ends using a molecular chain of an alkyl group, thereby providing a steric hindrance structure to the organic molecules.
Moreover, blue, green and red light emissions with higher color purity are necessary for applications to a full-color display or the like, but these problems are not yet sufficiently solved.